Can I pass a string, which is not previously stored in an array, as a parameter for a function?

Question

I wrote this function to remove the characters nay repeated from any string in c:

char *repeticoes(char *s){
    int i=0, j, cont=0;

    while(s[i]!='\0'){
        for(j=0;j<strlen(s);j++)
            if(s[j]==s[i] & j!=i)
                break;
        if(j==strlen(s))
            for(j=i;j<strlen(s);j++)
                s[j]=s[j+1];
        else
            i++;
    }
    return s;
}               

When I pass to it as a parameter an array s, s[20]="felicidade", I have the expected output that would be "eiidde", but when I pass as a parameter a vector *s="felicidade" or simply "felicidade" and have compiled, the program does not seem to respond.

Works normally:

int main(void){
    char s[20]="felicidade";    

    printf("%s",repeticoes(s));
}

do not work:

int main(void){
    char *s="felicidade";   

    printf("%s",repeticoes(s));
}

int main(void){
    printf("%s",repeticoes("felicidade"));
}